


Punchdrunk

by hovercraft



Category: Fate/Grand Order, Fate/stay night & Related Fandoms
Genre: Alternate Universe - Cyberpunk, Cyberpunk, M/M, underground fighting
Language: English
Status: Completed
Published: 2021-02-12
Updated: 2021-02-12
Packaged: 2021-03-18 09:33:35
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,656
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29366322
Author URL: https://archiveofourown.org/users/hovercraft/pseuds/hovercraft
Summary: Diarmuid earns his money in the fighting rings underground their dystopian city, but meets an opponent who--surprisingly--doesn't wish to fight him.A Valentine's Day Exchange fic.
Relationships: Cú Chulainn Alter | Berserker/Diarmuid Ua Duibhne | Lancer
Comments: 1
Kudos: 18





	Punchdrunk

He needed the money.

That was how he justified it to himself. Diarmuid had grown up a fighter and every profession he took made use of those skills, from surveillance to security, and now he was taking cash for a cage match in an underground ring of fighters. All he had to do was survive the fight with the reigning champion to collect his money, he didn’t even have to win— getting beat up was an easy gig to take on, all things considered. In this wasteland of metal and circuitry, the strong survived and the weak adapted. Diarmuid didn’t have many cybernetic enhancements, but he did have the necessary equipment for fighting— shock absorption, arm enhancements to make his punches strong enough to crack bone, an interface programmed into his back that allowed him to install new hardware and software if he needed it. That sort of thing.

Some fighters went all out, followed the philosophy that if the brain was just piloting a meat suit, why not upgrade it? So when he entered the locker room leading to the arena, he expected to fight absolute monsters. People with metal jutting out of every part of their body, optic LEDs replacing their eyeballs. He was surprised to find his opponent _looking_ like skin covered everything.

That, of course, was merely because he liked his tattoos and wanted to keep them. That didn’t mean that _everything else_ wasn’t upgraded beneath that skin. There were rumors that Cu was basically an armored titan beneath that, and Diarmuid felt his survivability chances shrink by the minute— not that he could afford to back out. He pressed a small switch behind his ear and held it down; sending a message to his friend that he’d be home late tonight and if he could prepare some bandages.

That was when Cu called off the fight.

Diarmuid looked at him like he was crazy. The entire ring started erupting in jeers and disappointment at the loss of revenue. Cu’s manager, a pink-haired woman, demanded to know what he was doing— do you have any idea how many people she’ll need to pay back for their bets?! Cu remained resolute, though. He wouldn’t fight Diarmuid.

It would be a while before Diarmuid found out why, either.

—

When he got back from the underground fighting ring, Arthur, his roommate, was waiting there for him with the requested bandages and bags of ice but was surprised to see him undamaged. Arthur looked hopeful.

“You won your fight?”

“My opponent called it off,” Diarmuid opened the fridge and pulled out the remaining bottle of green tea. “and I have no idea why.”

“Maybe he knows you from somewhere and felt bad beating you up?” Arthur asked, hopefully. Diarmuid shook his head, though. He’d never seen Cu before a day in his life.

“I’ll have to go back if I want to make rent, but hopefully the same guy won’t be there. I don’t think he can call off a fight a second time…”

“I can just pay rent this month, you know…”

Diarmuid sat next to Arthur and pat his shoulder. “Don’t worry about it. I know how hard it is, now that you’ve contracted that virus from god-knows-where... you haven’t been in the ring ever since that incident.”

Arthur froze, biting his lip. “Yeah…”

“Just leave it to me. I’ll go back tomorrow night.”

Arthur understood Diarmuid’s intentions, but just because he was an expert fighter didn’t mean he could survive everything. He’d been told of the titan of a man with blue hair, nobody could survive that without a trip to the hospital. He just wished he could fix up everything on his own, but the virus that he’d contracted within his software… it was making him glitch out and changing him emotionally, he couldn’t handle things right now until it got fixed.

He had to rely on Diarmuid this time.

—

The next day at the fighting ring, Diarmuid was pulled aside into a little alcove by the very man he’d been brought in to fight. Cu Chulainn.

Wordlessly, Cu pulled a wallet clip from the back of his pocket and counted off bills. Thousands of dollars, held by that tiny metal clip. He shoved it into Diarmuid’s hands.

“Don’t fight me today. Go home.”

“I—” Diarmuid was flabbergasted. “Why? What’s making you do this?”

“If I fight you, I’ll kill you in there. Just take the money and go.”

“You’re not known for your sympathy…”

“You’re not known for winning,” Cu bit back, but Diarmuid withstood the cruel taunt.

“Meet me in the showers afterward, then. I still want to talk to you about why.”

“… fine. But deposit the money first so you have credits.”

—

Paper cash was rare these days, so Diarmuid had done as he was told and deposited it onto his card. He went straight back to the showers, though, sitting on a metal bench as he waited for the fighters to come in after their battles in the ring. The sounds of crunching bone and pain rang in his ears from outside. If he’d fought Cu, there was no doubt those would be his bones, his pain, his agony. In fact, no one had entered the showers after their fights with Cu. If Diarmuid had to guess, he probably beat all of his opponents straight into the hospital.

It was just Cu coming in once the final bell rang.

He was covered in blood and oil, scratches marking up his chest but none so deep that it would do some damage to him. Little bits of shrapnel clung to his skin as he stood underneath the showerhead and brushed it all off, Diarmuid crossing his arms and standing up and walking over. He was dressed in a sleeveless green shirt that showed off his augmented arms, and tight black pants.

“Why do me so many favors?”

“You’ve got a pretty face. Hate to ruin it. That’s all.”

Diarmuid cocked his head. “Anyone in the world could tell you’re lying,” Diarmuid leaned in, just far enough out of the water. “Why?”

“Because… I owe you.”

“I don’t remember you.”

“You never saw me like this before.”

“…”

“It was a long time ago. I got my shit wrecked by a low-time gang. You were the one who took me to the underground hospital. That’s where I got upgraded— I bet you thought you’d never see me again, huh? I was real fucked up.”

True, Diarmuid had brought a blue-haired man into a hospital once, but he looked so different from the man before him that he never would have guessed— and blue hair wasn’t exactly uncommon these days. Still, he kept his response quiet and his surprise minimal, trying not to look overly shocked at the memory.

“And now you’re paying your debt to Medb?”

“She’d have me pay it through fucking her, but I chose to fight.”

“Must piss her off,” Diarmuid said quietly.

“I… never forgot… your face.”

There was something sentimental in Cu’s voice, even if he was so cruel he’d beat a hundred men to the brink of their lives, he still felt something special for Diarmuid. Something he wanted to pay back… through money, at least. He wasn’t sure Diarmuid would let him pay him back any other way.

Still, when the water was turned off, Diarmuid approached him and gently cupped his cheek. “I’m glad for the money, but… will she make you go back to her place after this?”

“Mhm.”

“Why not come to mine instead? Tell her you’re out on a run.”

Cu considered his options…

… and accepted.

—

Diarmuid thought they’d be talking over coffee, not—

He wriggled his hips under Cu’s forceful touch, wrapping his legs around his neck as Cu bit the inside of his thigh.

“You’re not giving me a blowjob with those teeth,” Diarmuid snapped, and Cu, for whatever reason, laughed.

“I guess not.”

Diarmuid pulled his legs off of him, pushing his foot into Cu’s chest so that he’d lay back against the couch. He crawled up and over him— god, he’d been so touch-starved lately that he’d take it from a monster of a man, but Cu’s interest was thoroughly betrayed the moment he entered the apartment, pinning him roughly against the door and invading his mouth with his tongue. His hand wandering around the inside of his shirt was already maddening, but Diarmuid was far from a passive player in this situation. He’d seen the outline of Cu’s pants and he wanted to see just what was inside.

Toying with the button and undoing his zipper, he was surprised to see this was the one thing on Cu that wasn’t augmented— because it didn’t have to be. Cu’s cock was heavy in his hands, and as he stroked it, he could feel himself— embarrassingly— salivate. Cu was just watching him with a simple curiosity as Diarmuid took him into his mouth, Cu rolling his head back as if he was used to this kind of treatment, but not unengaged with it at all.

“Does she…?” Diarmuid parted his lips to speak for just a moment, before setting back to the task.

“I don’t let her,” Cu said firmly.

“I see…”

Diarmuid wet his lips and lowered his head just a little bit more each and every time, his drool running down the side of Cu’s dick, making every pass a little easier. Though other lovers had noticed it, he never admitted to anyone before that he didn’t have a gag reflex to speak of. Cu threw his head back and shoved Diarmuid’s head down, firmly pressed up to the base and squishing his nose against him. He held him there, roughly, for a few moments before Diarmuid had to pull off and catch his breath.

“You’re—”

“You should’ve expected some roughness.”

“I’m not complaining.”

“Get back to it, then.”

With each suck, with each dip of his head, he could feel Cu tense up from the hand that he held over his abdomen. He was truly relaxed, but his pleasure was building. For some reason, it gave Diarmuid a bit of pride knowing he could tame such a beast as him with just this. As he took him with ease, stretching his jaw to the point of soreness, he wondered how much stamina someone like Cu could have, until the man roughly grabbed his dark locks and began to thrust into his mouth on his own. Apparently, Diarmuid had been going too slow for him.

Judging by the soft grunts and sighs, he was close. Diarmuid braced himself and sure enough, he could taste something bitter at the back of his tongue as Cu came, holding himself in place for as long as he could before he had to pull off. Cum dribbled down the side of his chin as he shamefully wiped it away.

“This better not be what the money was for…”

“No,” Cu said, leaning back, arm resting over the edge of the sofa. “Not at all.”

“Can you go again?”

“What for?”

“I’d…” Diarmuid paused. “I’d like to ride you.”

“You say it so embarrassedly. Nothing would piss off Medb more than to know I’ve been sleeping around.”

“Ah…”

“I’m not saying no.”

Diarmuid’s head shot up, before he relaxed and crawled over Cu’s body, dipping down for a kiss. Apparently, Cu didn’t mind the bitterness on his tongue at all, because he was more invasive, hungrier than Diarmuid expected him to be after all of that. As they made out atop the sofa, Diarmuid prayed for Arthur to stay busy somewhere else long enough for him to ride his heart out. He hadn’t been touched in so long that he had no problem using Cu to help himself. 

Besides, Diarmuid had special upgrades that allowed him to be proficient at this, at least.

Cu gripped his hips, noting that there had to have been hard metal beneath the soft tissue he could firmly squeeze.

“An upgrade that allows me to run faster,” Diarmuid answered before he could ask. “But it comes in handy for this, too.”

It was Cu’s turn to unwrap Diarmuid from his clothing, slim-fitting leather pants coming undone and slipping down his thighs. Cu could feel it— the mechanical shift in his legs, the augmentations, but it would no doubt help him in raising those hips in other ways, too.

“You could’ve put up a good fight…” Cu said quietly, hands running down his abdomen. “You’ve had a look in your eyes this entire time that showed off how badly you wanted to. You want to prove you’re better than being paid off, don’t you?”

“… my pride gets in the way, sometimes.”

“It’s better that way. Fight me in a different way.”

Diarmuid lubricated his fingers with a bottle that had been stashed away in the table beside the sofa, knees planted on either side of Cu. He took in the full sight of his body as he inserted his fingers into himself— god, Cu was beautiful, even the mess of machinery he’d become was still gorgeous. No wonder Medb modified him to her specifications. Those talons on the end of his fingers would make this problematic, though, so he knew better than to ask.

Preparing himself, he slid down onto Cu’s cock and sighed in sweet relief. He’d been aching, waiting for this moment from the first moment he saw Cu. He wanted to be taken roughly in the center of the ring, sure, but that wasn’t going to happen, so on his sofa while his roommate was gone would have to do. He lowered his hips onto him with a soft smack before raising himself and doing it again— as seamlessly as an engine, thanks to those legs of his. Diarmuid’s golden eyes met Cu’s red ones. He wondered if those eyes were the only natural thing left in Cu, aside from his mind.

Cu was patient with him. He stretched back, hands on his hips, guiding him as he bounced in his lap. Coming once already, it seemed he was in no hurry, so Diarmuid could work out all of his physical frustrations on him. The touch, the sensation he’d gone without, the attraction he’d never really felt before… other people couldn’t compare to Cu Chulainn, apparently, as Diarmuid took him inside of him again and again, but would he be allowed this again? Wasn’t his boss a jealous woman?

Cu didn’t care. Cu didn’t have time to care. He let Diarmuid ride him like a stallion and bucked occasionally to make the other hum in contentment. Diarmuid could only think of the lack of sensation once this was all over, and tried to stave off his orgasm for as long as he could, but Cu was reaching his limit yet again. Even with that invigorated body, it seemed the sight of Diarmuid, the feel of him running his hands down his tattooed torso was too much.

Diarmuid came first but elegantly kept moving his hips until the very end, until Cu finished. The two looked at one another, the mess, and Diarmuid sheepishly pulled off of him to show him to the showers, but Cu grabbed his wrist and pulled him in with him.

He’d have to go back to the fighting ring tomorrow, though. Diarmuid had something to prove.

—

As Cu Chulainn geared up for his next fight, Medb watched the ring from above, on a seat meant for sponsors to watch their fighters claim their victories. Diarmuid wasn’t on the roster today, but he’d walked out with Cu. Hm…?

They seemed to be saying something to one another before Cu grabbed him by the chin and kissed him in full view of her.

Her outrage would be the source of his mirth throughout the fight, and even as Diarmuid walked back from the ring, he knew he was in deep trouble.


End file.
